Longitudinal observations of typical English voicing acquisition in a 2-year-old child: Stability of the contrast and considerations for clinical assessment

The nature of data reporting in previous literature on typical voicing acquisition left aspects of the developmental process unclear and limited clinical applicability. This work extends a previous four-month group study to present data for one child over 12 months.

Words containing initial /b p d t/ were elicited from a monolingual English-speaking 2-year-old child biweekly for 25 sessions. Voice onset time (VOT) was measured for each stop. For each consonant and recording session, we measured range as well as accuracy, overshoot and discreteness calculated for means and individual tokens.